boardman



H.A.BOARDMAN.

Calipers.

Patented Feb. 5,1867.

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IMPROVEMENT IN OALIPERS.

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1'0 ALL WHOM IT MAY CONCERN:

Be it knofwn that I, H. A. BOARDMAN, of New Haven, in the county'of NewHaven, and State of Connec= ticut, have invented new and improvedCalipers; and I do hereby declare that the following is a full, clear,and exact description thereof, which will enable others skilled in theart to make and use the same, reference being had to the accompanyingdrawings, forming part of this specification: I

The present invention consists principally in the combination, with thearms of the calipers, of a screwthreaded shaft that at one end issecured to a loop swivelled or pivotedto one of the arms of thecalipers, and, passing therefrom loosely through a loop similarly hungto the other arm, has screwed upon its outer and loose end a milled nut,by the turning of which upon the said screw-shaft, either to the rightor left, as the case may be, the arms of the calipers can be eitherclosed or allowed to open by the action of a spiral or other springsuitably attached or connected to them therefor.

This invention also consistsin a novelomannerof connecting and combiningthe arms and spiral spring of the calipers together, as will behereinafter explained. In the accompanying plate of drawings my improvedcalipers are illustrated- Figure 1 being a front view ot the same with aportion in section to show the arrangement of the spiral spring forthrowing open the arms of the calipers; and

Figure 2, an edge view with the same portion in section as that shown infig. 1, but in a (lifi'erent plane.

Similar letters of reference indicate like parts.

A A, in the drawings, represent the twoarms of the calipers, both ofwhich are made of a similar curved shape, and are hung at one end to andupon a common centre-pin or pivot, B, by which they are also secured andheld together with a barrel, collar, or ring, (1, between the two,forming a suitable box or casing, D, to receive and hold a spiralspring, E, which surrounds the said centre-pin B Each end of the spiralspring E is made of a hook-shape, so as to interlock with pins a oi: thecaliper-arms, one with one of the said arms and the other with the otherof the same, in such a manner as to swing or open the arms from eachother by its pressure or tension. F a screw threaded shaft, which at oneend is secured to a loop, G, swivellcdor pivoted to one of the arms ofthe calipers. This shaft F passes loosely through another l'oop, H,swivelled to the other arm, when upon its outer end a milled nut, I, isscrewed, by the'turning of which, either'to the right or left, as thecase may be, the arms of the calipers can be closed or allowed toopen'from each other by the action of the spiral spring E, according asmay be necessary or desirable, the said nut holding the arms of thecalipcrsx at whatever position they may be brought or adjusted by theturning of the same. By passing the screw-threaded shaft through a loopswiyelled to one of ,the arms of the calipers, and hanging or securingit to a similar loop of the other, all strain upon the said shaft isavoided, and it is capable of adjusting itself in position according asthe arms of the calipers are more or less open. By hanging thespiralspring E, used in the manner above described, to .the two arms of thecalipers, or in an equivalent manner thereto, I- a m'enabled to use abarrel or.

collar, C, for enclosing it, made in one entire or continuous piece ofmetal or other suitable material, whereas, in all calipers, as hithertomade, as the spring. was hung or connected to the barrel or collar insome manner, such barrel usually constituted a part or was formedupoupnc of the arms, and at some points of its length was slotted oropened. In order to fully; insure the retention of the barrel C inposition between the arms of the calipers, without requiring the arms tobe tightened upon it by their centre screw to such a degree as toprevent their free action or play, I deem it best to bevel the edges ofthe collar as well as the surface of the arms with which it comes incontact to such an extent and in such directions as to prevent thecollar from slipping or moving laterally evon'if the arms are leftrather loose or free to turn, the advantages and importance of which areobvious.

Although I have herein particularly explained my improvements inconnection with calipers, it is obvious that they may be used or adaptedas well to compasses and other similar instrument s.

What I claim as new, and desire to secure by Letters Patent, is-

The barrel or collar C when made in one'entire or cont nuous piece andindependent oh the caliper arms, and secured thereto substantially asand for the purpose described.

' H, A. BOARDMAN.

Witnesses PHILIP Penn, CHARLES C. Btsrennsr,

